The results show that the coagulant dose and dye concentration significantly affect the color removal performance of O. basilicum and the dye concentration is the most significant parameter. However, pH (withinthe selected range) is not a significant factor in the color removal efficiency of the natural coagulant. The parameters also have nointeractive effects on the response. This means that the modifica-tion of one of the factors does not affect the other factors insidethe working region. Negative coefficient values of the individualfactors, A, B and C, indicate that the factors negatively affect the response and by increasing these terms the color removal percentage may decrease.